先放源代码,还没开始看,等看完再来写注释及讲解。
#include
#include
#include
#include
#include "MQTTClient.h"
#define MQTT_Uri "localhost" // MQTT服务器的地址和端口号
#define ClientId "ubuntu16" // ClientId需要唯一
#define UserName "pi" // 用户名
#define PassWord "12345678" // 用户名对应的密码
// 失去连接回调函数
void connect_lost(void *context, char *cause)
{
printf("Connection lost,The reason: %s \n",cause);
}
// 收到主题信息回调函数
int message_arrived(void *context, char *topicName, int topicLen, MQTTClient_message *message)
{
printf("Receive topic: %s, message data: \n", topicName);
printf("%.*s\n", message->payloadlen, (char*)message->payload);
MQTTClient_freeMessage(&message);
MQTTClient_free(topicName);
return 1;
}
// 主题发布成功回调函数
void delivery_complete(void *context, MQTTClient_deliveryToken dt)
{
printf("publish topic success,token = %d \n", dt);
}
int main(int argc, char* argv[])
{
// 1、定义一个MQTT客户端结构体指针
MQTTClient client;
// 2、创建一个MQTT客户端
int rc;
if ((rc = MQTTClient_create(&client, MQTT_Uri, ClientId, MQTTCLIENT_PERSISTENCE_NONE, NULL)) != MQTTCLIENT_SUCCESS)
{
printf("Failed to create client, return code %d\n", rc);
exit(EXIT_FAILURE);
goto exit;
}
// 3、创建一个MQTT连接配置结构体,并配置其参数
MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
conn_opts.username = UserName; // 用户名
conn_opts.password = PassWord; // 用户名对应的密码
conn_opts.keepAliveInterval = 60; // 心跳时间
conn_opts.cleansession = 1; // 清除会话
// 4、设置MQTT连接时的回调函数
if ((rc = MQTTClient_setCallbacks(client, NULL, connect_lost, message_arrived, delivery_complete)) != MQTTCLIENT_SUCCESS)
{
printf("Failed to set callbacks, return code %d\n", rc);
rc = EXIT_FAILURE;
goto destroy_exit;
}
// 5、开始连接到MQTT服务器
if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS)
{
printf("Failed to connect, return code %d\n", rc);
exit(EXIT_FAILURE);
goto destroy_exit;
}
// 6、定义一个主题消息存储结构体
MQTTClient_message pubmsg = MQTTClient_message_initializer;
char mag_data[] = "I am Ubuntu16.";
pubmsg.payload = mag_data;
pubmsg.payloadlen = (int)strlen(mag_data);
pubmsg.qos = 1; // qos等级为1
pubmsg.retained = 0; // 服务器不保留消息
MQTTClient_deliveryToken token; // 标记MQTT消息的值,用来检查消息是否发送成功
// 7、发布主题信息
if ((rc = MQTTClient_publishMessage(client, "pubtest", &pubmsg, &token)) != MQTTCLIENT_SUCCESS)
{
printf("Failed to publish message, return code %d\n", rc);
exit(EXIT_FAILURE);
}
// 8、订阅主题
if ((rc = MQTTClient_subscribe(client, "subtest", 1)) != MQTTCLIENT_SUCCESS)
{
printf("Failed to subscribe, return code %d\n", rc);
rc = EXIT_FAILURE;
}
// 9、等待输入'Q'或'q'退出
printf("Press Q or q + to quit\n\n" );
int ch;
do
{
ch = getchar();
} while (ch!='Q' && ch != 'q');
if ((rc = MQTTClient_unsubscribe(client, "ubuntu16_subscribe")) != MQTTCLIENT_SUCCESS)
{
printf("Failed to unsubscribe, return code %d\n", rc);
rc = EXIT_FAILURE;
}
// 10、断开连接
if ((rc = MQTTClient_disconnect(client, 10000)) != MQTTCLIENT_SUCCESS)
{
printf("Failed to disconnect, return code %d\n", rc);
rc = EXIT_FAILURE;
}
destroy_exit:
MQTTClient_destroy(&client);
exit:
return rc;
}
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